This invention relates to pressurized systems used in the transfer of product, through hoses, to pressure vessels. More particularly, the invention relates to equipment used in the transfer of agricultural ammonia from storage tanks and wagon-mounted nurse tanks, and provides a safety device for bleeding off undesired liquid ammonia at the bottom of a hose bend.
Liquid anhydrous ammonia (NH,) has long been used as a fertilizer for corn, grains and other crops. The typical ammonia application system consists of a nurse tank trailed behind a tool bar which is attached to a tractor. Application rate is controlled by a meter. The nurse tank is a trailer-mounted pressure vessel which contains the ammonia in its liquid state. The ammonia flows through a hose from the tank to the meter, then through more hose to one or more dividing manifolds, and finally through suitable hoses to the applicator knives which inject the ammonia into the soil. Hoses are used at ammonia storage facilities to fill empty nurse tanks.
With all the hoses involved in ammonia application, frequent disconnections are required, and standard procedure is to evacuate the liquid from the hose in order to minimize the amount of liquid lost during disconnection. At times, however, a relatively small amount of liquid ammonia will remain at the bottom of a bend in the hose due to gravity. As a final step before disconnection, it should be easy to bleed off any small amount of liquid at that location. Due to the extremely hazardous nature of ammonia, however, the relatively small amount of hose bend bleed off liquid must be directed away from the face of the technician doing the bleed off.